This invention relates to programmable logic circuits which can perform a number of selectable logic functions. The invention is concerned with logic circuits which can dynamically be selectively programed to provide OR, NOR, AND and NAND functions and, if desired, exclusive OR (XOR) and exclusive NOR (XNOR) functions.
Logic circuits are currently used in many different types of apparatus, systems and in conjunction with other circuits. Logic circuits are used in and in conjunction with control circuits, calculators, computers, data processing systems and processors, to name a few uses. The more complex the systems, circuits or apparatus, the greater are the number and functional types of logic circuits generally required.
In many applications, a given logic circuit may be used for only a small portion of a time period during which a sequence of operations is being performed, remaining idle for considerable lengths of time. This results in uneconomical use of the logic circuits.
Moreover, in many applications a considerable number of logic functions must be performed, resulting in a need for numerous separate logic circuits. This results often in a large number of components. Such arrangements are often expensive to construct and can lead to relatively large space requirements.